全文获取类型
收费全文 | 7427篇 |
免费 | 360篇 |
国内免费 | 95篇 |
专业分类
电工技术 | 363篇 |
综合类 | 171篇 |
化学工业 | 1407篇 |
金属工艺 | 168篇 |
机械仪表 | 190篇 |
建筑科学 | 205篇 |
矿业工程 | 94篇 |
能源动力 | 200篇 |
轻工业 | 410篇 |
水利工程 | 56篇 |
石油天然气 | 73篇 |
武器工业 | 7篇 |
无线电 | 953篇 |
一般工业技术 | 1178篇 |
冶金工业 | 1557篇 |
原子能技术 | 158篇 |
自动化技术 | 692篇 |
出版年
2023年 | 46篇 |
2022年 | 110篇 |
2021年 | 150篇 |
2020年 | 92篇 |
2019年 | 83篇 |
2018年 | 104篇 |
2017年 | 102篇 |
2016年 | 164篇 |
2015年 | 137篇 |
2014年 | 219篇 |
2013年 | 350篇 |
2012年 | 282篇 |
2011年 | 352篇 |
2010年 | 293篇 |
2009年 | 285篇 |
2008年 | 320篇 |
2007年 | 261篇 |
2006年 | 283篇 |
2005年 | 218篇 |
2004年 | 202篇 |
2003年 | 211篇 |
2002年 | 223篇 |
2001年 | 229篇 |
2000年 | 161篇 |
1999年 | 206篇 |
1998年 | 618篇 |
1997年 | 404篇 |
1996年 | 291篇 |
1995年 | 175篇 |
1994年 | 166篇 |
1993年 | 137篇 |
1992年 | 86篇 |
1991年 | 89篇 |
1990年 | 66篇 |
1989年 | 64篇 |
1988年 | 66篇 |
1987年 | 55篇 |
1986年 | 55篇 |
1985年 | 48篇 |
1984年 | 44篇 |
1983年 | 48篇 |
1982年 | 49篇 |
1981年 | 52篇 |
1980年 | 28篇 |
1979年 | 34篇 |
1978年 | 21篇 |
1977年 | 29篇 |
1976年 | 65篇 |
1975年 | 17篇 |
1973年 | 16篇 |
排序方式: 共有7882条查询结果,搜索用时 156 毫秒
1.
Sangmin Lee Biao Che Meiling Tai Wanzhao Li Shin-Hyun Kim 《Advanced functional materials》2021,31(42):2105477
Hydrogel shells that compartmentalize the water core from the aqueous surrounding provide molecular selectivity on size and charge in transmembrane transport. It is highly demanding to produce thin hydrogel shells to minimize diffusion length and maximize core volume. Here, internal osmosis in water-in-oil-in-water-in-oil (W/O/W/O) triple-emulsion droplets is used to produce thin hydrogel shells enclosing a large water core. The triple-emulsion droplets are prepared to have an ultrathin middle oil layer using a capillary microfluidic device. The innermost water droplet has a higher osmolarity than the outer water layer containing photopolymerizable hydrogel precursors, which pumps water from the outer layer to the core through the ultrathin oil layer by the osmosis. Therefore, the outer layer gets thinner and hydrogel precursors are enriched while the size of the triple-emulsion droplets remains unchanged. Through photopolymerization of precursors and phase transfer from oil to water, hydrogel shells enclosing water core are produced in the water environment; the oil layer is ruptured for molecular exchange through the shells. The thickness and composition of the hydrogel shells are precisely controllable by the osmotic conditions. The shells show a high permeation rate due to the thinness as well as controlled cut-off threshold of permeation for neutral and charged molecules. 相似文献
2.
Masahiro Sato Miyu Koriyama Satoshi Watanabe Masato Ohtsuka Takayuki Sakurai Emi Inada Issei Saitoh Shingo Nakamura Kazuchika Miyoshi 《International journal of molecular sciences》2015,16(8):17838-17856
Some reports demonstrated successful genome editing in pigs by one-step zygote microinjection of mRNA of CRISPR/Cas9-related components. Given the relatively long gestation periods and the high cost of housing, the establishment of a single blastocyst-based assay for rapid optimization of the above system is required. As a proof-of-concept, we attempted to disrupt a gene (GGTA1) encoding the α-1,3-galactosyltransferase that synthesizes the α-Gal epitope using parthenogenetically activated porcine oocytes. The lack of α-Gal epitope expression can be monitored by staining with fluorescently labeled isolectin BS-I-B4 (IB4), which binds specifically to the α-Gal epitope. When oocytes were injected with guide RNA specific to GGTA1 together with enhanced green fluorescent protein (EGFP) and human Cas9 mRNAs, 65% (24/37) of the developing blastocysts exhibited green fluorescence, although almost all (96%, 23/24) showed a mosaic fluorescent pattern. Staining with IB4 revealed that the green fluorescent area often had a reduced binding activity to IB4. Of the 16 samples tested, six (five fluorescent and one non-fluorescent blastocysts) had indel mutations, suggesting a correlation between EGFP expression and mutation induction. Furthermore, it is suggested that zygote microinjection of mRNAs might lead to the production of piglets with cells harboring various mutation types. 相似文献
3.
Ming-Puu Chen Asta Y. Z. Lord Yu-Yao Cheng Ku-Chou Tai Wen-Harn Pan 《Journal of Computer Assisted Learning》2020,36(3):383-396
Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies. 相似文献
4.
Mizuki Tenjimbayashi Sadaki Samitsu Yuko Watanabe Yasuyuki Nakamura Masanobu Naito 《Advanced functional materials》2021,31(21):2010957
Liquid marble (LM) is a droplet that is wrapped by hydrophobic solid particles, which behave as a non-wetting soft solid. Based on these properties, LM can be applied in fluidics and soft device applications. A wide variety of functional particles have been synthesized to form functional LMs. However, the formation of multifunctional LMs by integrating several types of functional particles is challenging. Here, a general strategy for the flexible patterning of functional particles on droplet surfaces in a patchwork-like design is reported. It is shown that LMs can switch their macroscopic behavior between a stable and active state on super-repellent surfaces in situ by jamming/unjamming the surface particles. Active LMs hydrostatically coalesce to form a self-sorted particle pattern on the droplet surface. With the support of LM handling robotics, on-demand cyclic activation–manipulation–coalescence–stabilization protocols by LMs with different sizes and particle types result in the reliable design of multi-faced LMs. Based on this concept, a single bi-functional LM is designed from two mono-functional LMs as an advanced droplet carrier. 相似文献
5.
6.
7.
8.
Hisamoto D. Umeda K. Nakamura Y. Kimura S. 《Electron Devices, IEEE Transactions on》1997,44(6):951-956
This paper describes the high performance of T-shaped-gate CMOS devices with effective channel lengths in the sub-0.1-μm region. These devices were fabricated by using selective W growth, which allows low-resistance gates smaller than 0.1 μm to be made without requiring fine lithography alignment. We used counter-doping to scale down the threshold voltage while still maintaining acceptable short-channel effects. This approach allowed us to make ring oscillators with a gate-delay time as short as 21 ps at 2 V with a gate length of 0.15 μm. Furthermore, we experimentally show that the high circuit speed of a sub-0.1-μm gate length CMOS device is mainly due to the PMOS device performance, especially in terms of its drivability 相似文献
9.
The photoelectrochemical behaviors of RuL2(NCS)2 dye-sensitized SnO2/TiO2 coupled solar cell was studied and compared with TiO2 single system. The coupled system shows higher incident photon-to-current conversion efficiency (IPCE) value than the single system. A maximum IPCE value in the coupled system with 3.5 μm-thick SnO2 and 7 μm-thick TiO2 attained 82.4% at 530 nm wavelength. The higher IPCE value in the coupled system is attributed to the charge separation by fast electron transfer process from the excited RuL2(NCS)2 dye to TiO2 to SnO2 in the system with different energy level. 相似文献
10.
阐述了企业人力资源投资财务评价应解决的两个重要问题:评价对象的分类和项目的财务现金流量的内容。 相似文献